This invention pertains to a system for optoelectronically sensing the entry of coins into a coin operated machine such as a slot machine (gaming machine) or vending machine. The coin entry sensing system in accordance with the invention has provisions for sensing and thwarting a customer attempt to draw the coin out of the slot, among other features.
Conventional means for sensing coin entry into the slot of coin operated machines have been mostly mechanical or electromechanical. A long familiar one of such known means has been a microswitch having a feeler arm normally extending horizontally into the vertical path of the deposited coin. The falling coin engages and turns down the feeler arm, thus activating the microswitch. The resulting output signal of the microswitch represents the acceptance of a coin. The coin subsequently releases the feeler arm and allows the same to return to its normal position for sensing the entry of the next coin.
This conventional coin entry sensing mechanism is open to tampering. A typical tampering with coin operated machines is to hang a coin with string; the coin is dropped into the slot and, after activation of the microswitch, is drawn out of the slot. Difficulties have been encountered in mechanically sensing the upward movement of the coin.
The applicant is aware of a recent development employing photodetectors for sensing the downward travel of the deposited coin at proper speed, with a view to the prevention of illicit activities on the part of the customer. The prior art optoelectronic sensing system employs three photodetectors, however, together with complex circuitry and so is not so inexpensive as can be desired. As a further drawback it is incapable of detecting the reverse or upward travel of the coin.
Another frequent mode of tampering with coin operated machines is the use of different size coins or bored coins of smaller denominations than the required one. The advent of a sensing system that can make the coin operated machine immune to all such acts of tampering has long been awaited in the industry.